1. Field of the Invention
The present invention relates to a radio network controller, a mobile station, and a mobile communication method.
2. Description of the Related Art
Conventionally, a service (Multimedia Broadcast Multicast Service, hereinafter, referred to as an “MBMS”) has been provided, in which multimedia contents are broadcasted or multicasted to plural mobile stations (3GPP TSG-RAN, “TS25.346 V6.1.0 Introduction of Multimedia broadcast multicast service (MBMS) in Radio access network (RAN)”, June, 2004). In the MBMS, a frequency at which data is transmitted by the MBMS is notified to the mobile station via a radio access network. Due to this, it is possible for the mobile station not receiving data currently through the MBMS to receive data through the MBMS by carrying out a frequency handover to the notified frequency.
However, the mobile station that has started to use a specific frequency at which data is transmitted through the MBMS continues to be present at the frequency also after data reception through the MBMS unless the communication quality at the frequency is deteriorated. Therefore, traffic concentrates on a specific frequency and a deviation in the traffic occurs among frequencies. Such a problem arises not only in the MBMS, but also, for example, when the mobile station receives data to be transmitted by using a specific frequency such as a case of a high speed downlink packet access (HSDPA) etc or the like. Concentration of the traffic on one part of the frequencies as described above brings about a waste in utilizing radio resources.